Gunner&#39;s ear-muffle.



W. S. FRANKLIN.

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UNITED STATES PATENT Ormes.

WILLIAM S FRANKLIN, OF SOUTH BETHLEHEM, OF ONE-HALF TO JOHN HENRY KLINCK,

CAROLINA.

PENNSYLVANIA, ASSIGNOB GUNNERS EAR-MUFFIEi.

Application led Inch 27, 1893..

.To all whom it may concern.-

Be it known that LWILLIAM S. FRANKLI of South Bethlehem, in the county of Northampleu, and in the State of Pennsylvania,

'have' invented certa'in new and useful Improvements. in Ear-Muilles; and I do hereby Serial Xo. 710,705. Cle model.)

phragms is such that while the diaphragm C can vibrate freely in response to sound-waves of ordinary intensity it will eomefinto com tact with the diaphragm D when waves of more than the desired intensity occur. The 55 u latter diaphragm,- being stiE and incapable 0F CHARLESTON, SOUTH declare that the following is a full, clear, and

exactdescription thereof, reference being had to the accompanying drawings, in which- Figure 1 is an enlarged section view of an of vibration, holds the former diaphragm and new; prevents it from transmitting the sound- News l 4waves beyond the desired'intensity to the air -within the funnel, and hence'prevents their 6c ear-umide embodying my invention, and Fig. 2 is a view-ol' two such mules mounted on a spring.

Letters of like name and kind refer to like parts in each of the iigures.

The object'of my invention is to provide a -device by which the ear can be protected from the sound of heavy concussione or from other lend sounds without interfering with the corn-V mnnication of lesser sounds thereto; and to such ends my invention consists in the earmule hereinafter specified.

In carrying my invention into practice I provide a casing preferably consisting of a funnel-shaped part-'A and a cap B, the latter being secured in place over the larger end of the former by a female screw-thread in the cap which is engaged by a mle screw-thread on the funnel. The cap preferably has an outwardly-flaring opening in its outer end. 0n tne larger end of the funnel and at the haseof the thread in the cap are formed plane surfaces a and b, respectively, which are, in effect, opposite shoulders. A preferably imperforate diaphragm C rests against the shoulder b, and a perforated diaphragm D rests against the shoulder a.- A space E is formed between the diaphragme C and D, as by interposing a washer F between such parts or by dishingthe diaphragm D. The diaphragms C and D, or at les'st the former, are preferably firmly clamped between the shoulders a, and b. The diaphragm C is so formed as to be capable of vibrating under the action of sound-waves. It may be formed' of sheet metal and is made thin enough to give it the desired sensitiveness to sound-waves. The diaphragm D, however, is so formed as to bc practically unresponsive to the vibrations of 5c sound-wesen The distance between the diatransmission to the ear. It also prevents the breakage of the diaphragm C under the 'action of violent sound-waves. I have found by practical experiment that with the proper adjnstmentof the diaphragme the sound of 65 the firing of cannon is prevented from reaching the ear, while ordinary conversation can be heard practically as well as usual.` The advantage of such result is obvious when vit is remembered that fin drum of the ear is often severely injur-r and even broken by such sounds as the concussione of large gu ns.

It is desirable to use two of my ear-mailles at the same time, and hence I mount two of them on a spring G, which is curved to pass over or behind the' head. The ends of the spring areformed into or attached to eyes g Vand g, which are adapted to vbe passed over the smaller ends of the funnels and to be locked against shoulders a and a' thereon by nuts a2 and a2, which engage screw-threads at the base of such ends. The smaller ends of the funuels are preferably of such size as to be readily received into and to completely fill the external orifices of the ears. y

In operation the smaller ends of the funnels are introduced into the external orifices of theears,sothat no sounds can enter the ears except through the funnels. `Vhen sounds@ occur, their waves enter the opening in thecap and strike the diaphragm C, causing it to vibrate. If such soundsl are below the ntensity the transmission of which it is desired to prevent, the diaphragm in its vibration does not strike the diaphragm D, and hence the 95 sound is perfectly transmitted .to the air within the funnel and by this medium reaches the ear. If, however, the sounds are suchAA that the diaphragm C vibrates beyond the normal amplitude, the letter strikes against' zoo '55 purpose.

the diaphragm D and is prevented from communicating such impulse to the air within the f unnei as to distress the ear.

it isooizxious that changes can be made in 5 the above-descrbed construction that are within thegscope of my invention. For instance, thecasing can be made of such a shape as to inclose the whole ear instead of being received into the ear. The diaphragm xo C can be either simple or compound, on it can be made thicker toward theedges than in the center. Wil-@netting or a strip of metal can be used in place of the perforated diaphragm D. When the diaphragm C is clamped be- 15 tween the shoulders a and b,'it can only vibrate until its fibers are stretched tant, and

. it will hence be unable to transmit sonndabei youd a given loudness or amplitude of vibration. The same effect is produced by a m diaphragm thatis thinned toward, the een A ter, even if such diaphragm is not clamped.

In such cases the diaphragm D may serve only toprevent breakage ofi-the diaphragm C andcan be emitted if it is not needed for such Having thus des( ribcd my invention, what I claim is 1. An ear-niuie consisting of the combina- Lion of a diaphragm and astop to limit the 3o amplitude of vibration of thediaphragm,sub stan-tially as and for the purpose described. 2. An ear-muiileconsisting'of the combina tion with a ehamberadapted to be placed in communication withthe ear, of a. diaphragm 35 in a wall eflsiich chamber whose vibrations are limited to a predetermined amplitude, whereby sounds belowa certain intensityare transmitted to and sounds of greater intensity a're prevented from, reaching the ear, substantially as described.

3. An ear-mnie consstingof the combination with a chamber adapted to be placed in communication with the ear, of a diaphragm in a wall of such chamber, and an abutment against which said diaphragm is adapted to strike when vibrated beyond a predetermined amplitude, substantially as described.

4. An ear-mtime consisting of the combimv tion with a chamber adapted to be placed in communication with the car, of a diaphragm situated within said chamber and against which such diaphragm is adapted to strike 4when vibrated beyond a predetermined amplitude, substantially as described.

5. An ear-maille consisting of the combina tion with a chamber adapted to be placed in communication with the ear, of a diaphragm in a wall of such chamber, and an abutment consisting of a perforated non-vibrating wall 6o adjacent to butv normally not touching said diaphragm, substantially as described.

In testimony that I claim Vthe foregoing as my invention I have signed my name in presence of two subscribing witnesses.

5 in a wall of such chamber, and an abutment i .WILLIAM s FRANKJIN. f

Witnesses:

H. S. WEBB, R. B. WILLIAnsoN. 1 Y

Imi 

